Under a cooperative agreement from NCI, this study will develop and test interventions for preventing cancers associated with tobacco use and dietar practices among Native American people. In a repeated measures, randomized blocks design, the study will evaluate interventions for tobacco use prevention and for dietary modification among Native American adolescents in the Northeastern United States. The study's planned interventions are based on theoretical concepts of social learning, bicultural competence, an non-Western ecology. Drawn from the investigators' current research, tobacco use preventive intervention will address smoked and smokeless products within a format of 15 initial sessions and semiannual booster sessions. Dietary modification intervention will follow the format of tobacco use prevention to help Native youths learn and apply health knowledge and principles of behavior change to improve their dietary habits Study sites are Native American agencies and programs in four metropolitan areas, Boston, New York, Philadelphia, and Providence, and in seven states, Connecticut, Maine, Massachusetts, New Jersey, New York, Pennsylvania, and Rhode Island. Randomly, participating sites will be divided into four conditions: tobacco use prevention intervention, dietary modification intervention, tobacco use prevention and dietary modification intervention combined, and no-intervention control. Process data gathered during intervention will measure the fidelity of the study's independent variables Before, after and semiannually following initial intervention, all subjects will complete outcome measures. Outcome measures will quantify cognitive, behavioral, and environmental variables for cancer risk reduction through tobacco use prevention and dietary modification. The proposed research was developed in collaboration with Native American organizations, agencies, reservations, tribal councils, and groups throughout the Northeast. Representing these sites, administrators and clinical staff have agreed to participate in the study.